In particular, in installations for the manufacture of containers such as bottles and for the packaging of products in such containers, the containers are moved by transfer or conveyor devices which are of many types (endless belt conveyors, notched wheels or wheels with arms, endless conveyors with turntables, pulsed air slides, inclined slides with movement by gravity, etc.).
In particular, at the entrance of an installation suitable for the manufacture of containers from preforms, the preforms must be fed one after the other without discontinuity and must be pushed in order to enter a loading device (for example into the peripheral notches of a loading wheel).
Currently, the correct characteristics for feeding preforms at the entrance of the installation are obtained by using a slide chute feed device: the preforms, taken to the top of the chute, slide, under the effect of gravity, on the slide on the two ramps on which they are supported, by their collar, in a substantially vertical position; taking account of the speed of grasping the preforms at the bottom of the chute which is substantially less than the speed of progress of the preforms on the chute, the preforms stack up after each other along the slide and the weight component of these stacked preforms on the slide forces the leading preform to enter the loading device.
The feed device assembly (not only the chute, but also the hopper for receiving preforms in bulk situated upstream of the chute, the preforms lift and certain appended devices) constitutes a voluminous unit and, in installations of very large capacity capable of producing several thousand, or even several tens of thousands of containers per hour, this unit has very large dimensions and, in particular, can have a height of several meters. This makes it indispensable to add appropriate safety equipment to the hopper (footbridge with guard rail, ladder with guard rail) for the supervision and maintenance personnel. This result of this is that the feed device assembly, generally metallic, is of very high cost and has large dimensions, at ground level and, in particular, vertically.
It can also be added that the preforms, in a substantially vertical position, are supported on the two ramps of the inclined slide only by two points of their collar and this mediocre support causes the preforms to progress on the slide in an irregular and rocking manner, which proves to be disadvantageous (risk of jamming in the slide or of ejection of preforms out of the slide).
From the document EP 0 452 857, there is also known a conveyor device of the aforesaid type which comprises two conveyors respectively equipped with two endless links which respectively have two moving facing lines which are substantially parallel and substantially horizontal and which are driven in the same direction and substantially at the same speed, these two lines being separated from each other by a distance greater than the diameter of the body of the containers and less than the diameter of the collar of the containers such that the containers are supported in a substantially vertical position on the two lines by their collar.
Even though this known device meets the expectations of users with regard to low manufacturing cost and low overall size, in particular vertical size, it does not however solve certain problems which arise in the phase of feeding preforms, in particular with regard to the elimination of undesirable preforms (defective preforms, preforms nested in each other, etc.).